Crude glycerol is available in bulk quantities as a by-product of such processes as soap and detergent manufacture, alcoholic beverage manufacture, fatty acid production and biodiesel manufacture. Biodiesel is a vegetable oil or animal fat derived fuel that can be used in diesel engines and heating systems. The fuel is renewable, non-toxic and its use results in lower harmful emissions. Consequently, biodiesel production worldwide has surged as an attractive alternative to expensive and polluting petroleum-based fuels. In 2008, the United States National Biodiesel Board reported that the production of biodiesel in the United States alone reached 2.24 billion gallons per year (see http://www.biodiesel.org/pdf files/fuelfactsheets/production capacity.pdf). With such large amounts of biodiesel being produced, the excess crude glycerol is superseding the demand for glycerol in such conventional applications as cosmetics, personal care products and pharmaceuticals. Further, the expensive and energy-intensive process of refining the crude glycerol for such uses precludes refinement as the complete solution for the excess glycerol.
There are various processes being evaluated to deal with the oversupply of crude glycerol including using the crude glycerol as animal feed (see for example, Cerrate et al. (2006) Int. J. Poult. Sci. 5:1001) and converting the crude glycerol into products such as 1,3-propanediol (see for example, Asad-ur-Rehamn et al. (2008) Journal of Chemical Technology & Biotechnology, 83(7):1072). However, the viability of these processes on a commercial scale may prove difficult to achieve and consequently, there remains a need for viable processes to convert the excess glycerol into high value products.